JPS631104Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an exhaust gas recirculation control valve that recirculates an appropriate amount of exhaust gas depending on the operating condition of an internal combustion engine. The present invention relates to a control valve device that prevents a reduction in exhaust gas recirculation amount and blockage caused by deposition.

FIG. 1 shows the valve seat portion of a conventional control valve, where 1 is a housing, 2 is a valve seat installed in the housing 1, and 3 is a valve that can be freely seated on the valve seat 2. is moved up and down by an appropriate valve operating mechanism that moves the valve 3 up and down depending on the state of the engine, and when the valve 3 is separated from the valve seat 2, exhaust gas is recirculated through the gap between the two. .

By the way, the shape of the valve seat 2 is naturally limited due to ensuring airtightness when the valve 3 is seated and restrictions on processing. The nozzle shape must be such that the gas passage 4 defined by the circumferential surface has a truncated cone shape, or a shape similar to the nozzle shape, so that the exhaust gas flows while touching the inner peripheral wall of the valve seat 2. Therefore, exhaust gas particles tend to adhere to and accumulate on the peripheral wall.

In addition, since the contact area of the valve seat 2 with the housing 1 is large, the conduction heat from the valve seat 2 to the housing 1 is also large, and therefore, the heat retention of the valve seat 2 is poor, so that heat is transferred through the valve seat 2. As the exhaust gas loses heat through heat transfer, the temperature decreases.
As the amount of carbon particles in the exhaust gas increases, it becomes easier for the particles to adhere, and as a result, the adhesion and deposition of carbon particles on the valve seat 2 is further promoted.

Of course, if the diameter of the valve seat 2 is large, the flow rate of the exhaust gas passing through it is also large, so the heat transfer from the exhaust gas to the valve seat 2 is also large, and the adhesion and accumulation of particles also affects the inflow amount. Although it does not have much of an effect, in the exhaust gas recirculation control valve, the diameter of the valve seat 2 is set small, so the flow rate of the exhaust gas is small, and in addition, the adhesion and accumulation of carbon particles has a large effect. This not only results in a reduction in the amount of exhaust gas flowing in, but also causes the valve seat 2 to become clogged within a relatively short period of time.

The present invention solves the above-mentioned problems of conventional control valves, and aims to prevent carbon particles in exhaust gas from adhering to and accumulating on the valve seat.

In order to achieve this objective, the present invention employs the following configuration.

That is, a thin orifice plate is arranged at a predetermined interval on the upstream side of the exhaust gas flow from the valve seat surface. Then, an orifice with an area smaller than the valve seat flow path area is formed in the center of this orifice plate,
Further, around this orifice, an introduction part having a mountain-shaped cross section that protrudes from the upstream side to the downstream side of the exhaust gas flow is formed.

The present invention having such a configuration operates as follows. That is, the exhaust gas containing carbon particles flowing toward the orifice plate has its flow direction once reversed by the introduction section, and then passes through the orifice and flows toward the valve seat. In other words, the flow direction of relatively heavy carbon particles is changed to the downstream side of the exhaust gas by this introduction part, making it difficult for them to flow into the orifice.

Next, an embodiment of the present invention will be described based on the drawings.
In FIG. 2, 100 is a housing, 101 is a valve seat provided at the exhaust gas inlet 102 of the housing 100, and 103 is a valve attached to the end of a valve stem 104, which can be freely seated on the valve seat 101. ing.

The provision of these is similar to the conventional example shown in FIG. 1, but the present invention is different in that an orifice plate 106 having an orifice 105 is provided.

The orifice plate 106 is installed upstream of the valve seat 101 in the inflow direction of the exhaust gas G, and the valve 103 is seated downstream of the valve seat 101.

The orifice plate 106 is formed from a thin stainless steel plate, and around the orifice 105 is provided an introduction part 107 that is convex toward the valve seat 101 side. This guiding portion 107 directs the exhaust gas G flowing into the housing 100 and toward the valve seat 101 from the outer peripheral wall 1.
08, that is, it is introduced along the surface that slopes upward in the drawing, changes its direction downward at the bottom, and is then led out along the inner peripheral wall 109, that is, the surface that slopes downward in the drawing, In other words, the purpose is to restrict the flow of exhaust gas G so as to bend the traveling path of exhaust gas particles, and therefore, the shape is not limited to the illustrated shape as long as it bends the traveling path of the particles.

The orifice plate 106 is arranged at a constant distance from the valve seat 101 to create a heat insulating space 110 between them.
By doing so, the amount of heat escaping from the orifice plate 106 can be suppressed as much as possible, and therefore the temperature of the exhaust gas G passing through the orifice 105 can be significantly suppressed. Therefore, an increase in the amount of carbon particles and an increase in the ease of adhesion caused by a decrease in the temperature of the exhaust gas G can be suppressed.

Incidentally, as a valve operating mechanism for moving the valve stem 104 up and down depending on the state of the engine, for example, one shown in FIG. 3 is used.

That is, in this valve mechanism, a case 113 is attached to a housing 100 via a heat insulating material 112, and a space formed by fitting a cover 114 to the case 113 is partitioned by a diaphragm 115, and a space is formed on the cover 114 side. A negative pressure chamber 116 is defined, a diaphragm 115 is sandwiched between pressure plates 117, and one end of a valve stem 104 is slidably supported on a fixed bearing 118 between the housing 100 and the case 113. A valve 103 fixed to a pressure plate 117 and attached to the other end of a valve stem 104 passing through a protector 120 is freely seated on a valve seat 101 provided in a housing 100, and further defines a negative pressure chamber 116. cover 1
14 and the diaphragm 115 have a spring 12
3 and a sensing pipe 124 attached to the cover 114.

Therefore, from the sensing pipe 124 to the negative pressure chamber 1
When negative pressure is transmitted to the spring 16, the diaphragm 115 resists the biasing force of the spring 123.
23 is displaced in the direction of compressing the spring 12.
The displacement of the diaphragm 115 stops when the urging force No. 3 and the negative pressure are balanced.

On the other hand, since the valve rod 104 also moves upward in the drawing in accordance with the displacement of the diaphragm 115, the valve 103 separates from the valve seat 101, and exhaust gas begins to flow in from the gap between the valve 103 and the valve seat 101. The upward movement of the valve stem 104 then stops when the diaphragm 115 stops.

As described above, in the present invention, a thin orifice plate is installed on the upstream side of the valve seat, and an orifice having an area smaller than the flow area of the valve seat is formed in the center of the plate. An introduction part having a mountain-shaped cross section that protrudes from the upstream side to the downstream side of the exhaust gas flow is formed around the orifice on the outer periphery of the orifice plate, so that the exhaust gas flowing inside the exhaust gas flow hole passage is formed around the orifice. The flow direction of the gas is changed from the upstream side to the downstream side by the introduction section having a mountain-shaped cross section, and the gas is then diverted from the flow direction to the opposite direction, and then flows to pass through the orifice. Therefore, due to the effect of this introduction part and the orifice, carbon particles are difficult to adhere to or accumulate on the orifice plate, and the contact area with other parts is also small, making it difficult for the orifice plate to lose heat. Even if the aperture is made smaller, the influence of adhesion and deposition of carbon particles will be small.

In addition, when forming the orifice plate, there is no need to consider airtightness when the valve is seated, and since it is a thin plate, there are no restrictions on processing.
It is also possible to provide an introduction section, which allows the exhaust gas to bend its path and then flow into the orifice, making it difficult for relatively heavy carbon particles to flow into the orifice. In conjunction with the above, adhesion and deposition of exhaust gas particles is suppressed to the utmost.

Moreover, by reducing the hole diameter of the orifice, the diameter of the valve seat can be made relatively large, so even if exhaust gas particles adhere to the valve seat as in the conventional case, their influence will be small and the flow rate of exhaust gas will be reduced. will be minor.

In the end, exhaust gas particles do not easily adhere to or accumulate on the orifice plate, and even if the same particles adhere to or accumulate on the valve seat as before, it will not have much of an effect, and the flow rate of exhaust gas will decrease. will be suppressed very slightly.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the vicinity of the valve seat of a conventional control valve, Fig. 2 is a sectional view showing the vicinity of the valve seat of the control valve according to the present invention, and Fig. 3 shows the valve operating mechanism of the control valve. FIG. 101... Valve seat, 103... Valve, 105... Orifice, 106... Orifice plate, 107...
Introduction.

Claims (1)

[Scope of utility model registration request] In an exhaust gas recirculation control valve for an internal combustion engine, a thin orifice plate is arranged in the exhaust gas inlet passage of the valve seat of the recirculation control valve at a predetermined interval from the valve seat surface to the upstream side of the exhaust gas flow. An orifice with an area smaller than the valve seat flow path area is formed in the center of the orifice plate, and a cross section protruding from the upstream side to the downstream side of the exhaust gas flow is formed on the outer periphery of the orifice plate. An exhaust gas recirculation control valve device, characterized in that a mountain-shaped introduction portion is formed around the orifice.